Conventionally, there is known a light-emitting apparatus that includes a blue LED (light-emitting diode, light-emitting element) in combination with a fluorescent material. In the light-emitting apparatus, light emitted from the blue LED is converted into light having a color such as yellow by the fluorescent material, and then blended with light which has been emitted from the blue LED but has not been subjected to conversion by the fluorescent material, so that light having a given color can be produced. The fluorescent material emits, when irradiated with excitation light emitted from the light-emitting element, fluorescent light having a longer wavelength than the excitation light. In the light-emitting apparatus adopting a configuration described above, light to be emitted has a color and brightness which are varied based on a balance between the light emitted from the blue LED and fluorescent light emitted from the fluorescent material. On this regard, it is important to control the balance between them.
For example, Patent Literature 1 discloses a method for manufacturing a light-emitting apparatus, which method is for manufacturing the light-emitting apparatus by adjusting a brightness of and a color of light to be emitted from the light-emitting apparatus. FIGS. 18(a) through 18(c) are views each showing a step of the method according to Patent Literature 1 for manufacturing a light-emitting apparatus 500.
As shown in FIG. 18(a), a given current is applied to a light-emitting apparatus blank 503 (light-emitting apparatus to which no coating agent is applied) so that white light 504 is emitted, which light-emitting apparatus 503 is formed by: mounting a blue LED 502 on a resin substrate 501; and sealing the blue LED 502 by a resin material containing a fluorescent particle. Then, the white light 504 emitted from a surface of the resin material is measured by a light-emission measurement apparatus 505.
A subsequent step of the method calculates, based on a measurement value of the white light 504 thus obtained by measurement with the light-emission measurement apparatus 505, a pigment particle and a film thickness each contributing to emission of pastel light having a desired intermediate color. The measurement value of the white light 504 is varied in a wavelength component and/or a luminance, depending on (i) a wavelength and a luminance of light emitted from the blue LED 502 constituting the light-emitting apparatus 503 or (ii) a density of the fluorescent particle contained in the resin material.
A subsequent step of the method controls, based on a result from the calculation, an applying apparatus 506 is controlled so that a coating material 507 is sprayed to a surface of the light-emitting apparatus blank 503, as shown in FIG. 18(b). By this, a coating film 508 made from the coating material 507 is formed on the surface of the light-emitting apparatus blank 503, as shown in FIG. 18(c). By above processes, the light-emitting apparatus 500 is manufactured. The light-emitting apparatus 500 can emit, from its surface, the pastel light having the desired intermediate color.
Patent Literature 2 discloses a method for manufacturing a light-emitting apparatus, which method includes: covering a blue LED by a buffer layer (light-transmissive resin); and then applying a fluorescent material to the buffer layer by an ink jet printing method. The method disclosed in Patent Literature 2 provides the blue LED in a package configured in a dot matrix manner, and then forms, above the package, the buffer layer made of an epoxy resin. Subsequently, the method discharges, via an ink jet printer head to only that part of the buffer layer which is formed above an aperture section of the package, alcohol which contains an organic fluorescent dye or a fluorescent particle, so that a fluorescent material is applied on the buffer layer.
After the above, a subsequent step of the method performs scanning by an optical sensor while the blue LED emits light, so as to store, in a memory, pieces of information on a color of the light emitted from the blue LED and on a position of the blue LED. Subsequently, a step of the method compares the color of light thus read out by the optical sensor with a referential color of emission light. In this case, if the fluorescent material is small in amount, the method calculates an amount by which the fluorescent material requires to be applied. Then, based on the amount thus calculated, a step of the method again applies, via the ink jet printer head to that part of the buffer layer which is determined to have the small amount of the fluorescent material, a desired amount of the fluorescent material. By above processes, the color of emission light is adjusted.